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Sun F, Zhao W, Shen H, Fan N, Zhang J, Liu Q, Xu C, Luo J, Zhao M, Chen Y, Lam KWK, Yang X, Kwok RTK, Lam JWY, Sun J, Zhang H, Tang BZ. Design of Smart Aggregates: Toward Rapid Clinical Diagnosis of Hyperlipidemia in Human Blood. Adv Mater 2022; 34:e2207671. [PMID: 36134528 DOI: 10.1002/adma.202207671] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 09/10/2022] [Indexed: 06/16/2023]
Abstract
Molecular aggregates with environmental responsive properties are desired for their wide practical applications such as bioprobes. Here, a series of smart near-infrared (NIR) luminogens for hyperlipidemia (HLP) diagnosis is reported. The aggregates of these molecules exhibit a twisted intramolecular charge-transfer effect in aqueous media, but aggregation-induced emission in highly viscous media due to the restriction of the intramolecular motion. These aggregates, which can autonomously respond to different environments via switching the aggregation state without changing their chemical structures are described, as "smart aggregates". Intriguingly, these luminogens demonstrate NIR-II and NIR-III luminescence with ultralarge Stokes shifts (>950 nm). Both in vitro detection and in vivo imaging of HLP can be realized in a mouse model. Linear relationships exist between the emission intensity and multiple pathological parameters in blood samples of HLP patients. Thus, the design of smart aggregate facilitates rapid and accurate detection of HLP and provides a promising attempt in aggregate science.
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Affiliation(s)
- Feiyi Sun
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
| | - Wei Zhao
- Department of Anesthesiology, Zhujiang Hospital, Southern Medical University, Guangzhou, 510280, P. R. China
| | - Hanchen Shen
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
| | - Ni Fan
- School of Chinese Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, 999077, P. R. China
| | - Jianyu Zhang
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
| | - Qingqing Liu
- School of Chinese Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, 999077, P. R. China
| | - Changhuo Xu
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
| | - Jiaming Luo
- Department of Anesthesiology, Zhujiang Hospital, Southern Medical University, Guangzhou, 510280, P. R. China
| | - Mengying Zhao
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
| | - Yuyang Chen
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
| | - Kristy W K Lam
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
| | - Xueqin Yang
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
| | - Ryan T K Kwok
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
| | - Jacky W Y Lam
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
| | - Jianwei Sun
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
| | - Hongfei Zhang
- Department of Anesthesiology, Zhujiang Hospital, Southern Medical University, Guangzhou, 510280, P. R. China
| | - Ben Zhong Tang
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong-Hong Kong-Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China
- School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology, The Chinese University of Hong Kong, Shenzhen, 518172, P. R. China
- Center of Aggregation-Induced Emission, South China University of Technology, Guangzhou, 510640, P. R. China
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Hänni M, Leppänen O, Smedby Ö. Postangioplasty Restenosis Followed with Magnetic Resonance Imaging in an Atherosclerotic Rabbit Model. Int J Biomed Imaging 2012; 2012:1-8. [PMID: 23316216 PMCID: PMC3536348 DOI: 10.1155/2012/747264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 12/03/2012] [Accepted: 12/05/2012] [Indexed: 11/27/2022] Open
Abstract
Rationale and Objectives. Testing a quantitative, noninvasive method to assess postangioplasty vessel wall changes in an animal model. Material and Methods. Six New Zealand white rabbits were subjected to atherosclerotic injury, including cholesterol-enriched diet, deendothelialization, and percutaneous transluminal angioplasty (PTA) in the distal part of abdominal aorta (four weeks after deendothelialization). The animals were examined with a 1.5T MRI scanner at three times as follows: baseline (six weeks after diet start and two days after PTA) and four weeks and 10 weeks after-PTA. Inflow angiosequence (M2DI) and proton-density-weighted sequence (PDW) were performed to examine the aorta with axial slices. To identify the inner and outer vessel wall boundaries, a dynamic contour algorithm (Gradient Vector Flow Snakes) was applied to the images, followed by calculation of the vessel wall dimensions. The results were compared with histopathological analysis. Results. The wall thickness in the lesion was significantly higher than in the control region at 4 and 10 weeks, reflecting induction of experimentally created after-angioplasty lesion. At baseline, no significant difference between the two regions was present. Conclusions. It is possible to follow the development of vessel wall changes after-PTA with MRI in this rabbit model.
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Minalga E, Rose J, Choi SE, Jeong EK, Kholmovski E, Vijayakumar S, Parker D, Hadley R. A 20-channel coil for improved magnetic resonance imaging of the optic nerve. Concepts Magn Reson Part B Magn Reson Eng 2011; 39B:26-36. [PMID: 21603068 PMCID: PMC3096670 DOI: 10.1002/cmr.b.20186] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
AbstractThe purpose of this thesis is to design and construct a radio‐frequency coil for imaging the optic nerve on a 3 Tesla magnetic resonance imaging scanner. The goal of the work is to increase signal‐to‐noise ratio from the orbits to the optic chiasm, compared to the current coil designs used for imaging the optic nerve. The coil utilizes a mask fiberglass former, with the coils designed to obtain the most signal‐to‐noise ratio at the optic nerve. The design uses a 20‐channel radio‐frequency coil array, with coil placement along the optic nerve. The signal‐to‐noise ratio achieved was compared to the clinically available 12‐channel head coil. The improved signal‐to‐noise ratio allowed for higher resolution, diffusion tensor imaging, and parallel imaging superior to the current standard. Patient images showed that the plaques evidenced in the images correspond well to patient histories of bilateral and unilateral disease of the optic nerves. This optic nerve coil has shown improved patient care after increasing the diagnostic power of the magnetic resonance imaging scanner. © 2011 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 39B: 26–36, 2011
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Affiliation(s)
- Emilee Minalga
- Department of Radiology, University of Utah, 729 Arapeen Dr., Salt Lake City, Utah 84108
| | - John Rose
- Department of Neurology, University of Utah, 729 Arapeen Dr., Salt Lake City, Utah 84108
| | - Seong-Eun Choi
- Department of Radiology, University of Utah, 729 Arapeen Dr., Salt Lake City, Utah 84108
| | - Eun-Kee Jeong
- Department of Radiology, University of Utah, 729 Arapeen Dr., Salt Lake City, Utah 84108
| | - Eugene Kholmovski
- Department of Radiology, University of Utah, 729 Arapeen Dr., Salt Lake City, Utah 84108
- Department of Neurology, University of Utah, 729 Arapeen Dr., Salt Lake City, Utah 84108
| | - Sathya Vijayakumar
- Department of Radiology, University of Utah, 729 Arapeen Dr., Salt Lake City, Utah 84108
- Department of Neurology, University of Utah, 729 Arapeen Dr., Salt Lake City, Utah 84108
| | - Dennis Parker
- Department of Radiology, University of Utah, 729 Arapeen Dr., Salt Lake City, Utah 84108
| | - Rock Hadley
- Department of Radiology, University of Utah, 729 Arapeen Dr., Salt Lake City, Utah 84108
- Department of Neurology, University of Utah, 729 Arapeen Dr., Salt Lake City, Utah 84108
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Abstract
Magnetic resonance imaging (MRI) is a powerful medical diagnostic imaging modality for integrin targeted imaging, which uses the magnetic resonance of tissue water protons to display tissue anatomic structures with high spatial resolution. Contrast agents are often used in MRI to highlight specific regions of the body and make them easier to visualize. There are four main classes of MRI contrast agents based on their different contrast mechanisms, including T(1), T(2), chemical exchange saturation transfer (CEST) agents, and heteronuclear contrast agents. Integrins are an important family of heterodimeric transmembrane glycoproteins that function as mediators of cell-cell and cell-extracellular matrix interactions. The overexpressed integrins can be used as the molecular targets for designing suitable integrin targeted contrast agents for MR molecular imaging. Integrin targeted contrast agent includes a targeting agent specific to a target integrin, a paramagnetic agent and a linker connecting the targeting agent with the paramagnetic agent. Proper selection of targeting agents is critical for targeted MRI contrast agents to effectively bind to integrins for in vivo imaging. An ideal integrin targeted MR contrast agent should be non-toxic, provide strong contrast enhancement at the target sites and can be completely excreted from the body after MR imaging. An overview of integrin targeted MR contrast agents based on small molecular and macromolecular Gd(III) complexes, lipid nanoparticles and superparamagnetic nanoparticles is provided for MR molecular imaging. By using proper delivery systems for loading sufficient Gd(III) chelates or superparamagnetic nanoparticles, effective molecular imaging of integrins with MRI has been demonstrated in animal models.
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Briley-Saebo KC, Mani V, Hyafil F, Cornily JC, Fayad ZA. Fractionated Feridex and positive contrast: in vivo MR imaging of atherosclerosis. Magn Reson Med 2008; 59:721-30. [PMID: 18383304 DOI: 10.1002/mrm.21541] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Macrophages have been identified as a critical factor in the pathogenesis of atherosclerosis. Ultrasmall iron oxide particles (USPIOs) have been used to passively target intraplaque macrophages. For dextran-based USPIOs, uptake into macrophages may be modulated by particle size. The aim of the current study was to test the efficacy of fractionated Feridex with respect to macrophage uptake in atherosclerotic rabbits. Fractionation of Feridex resulted in a 15-nm USPIO that exhibited a blood half-life of 15.9 h and liver retention of 6.4%. Blood clearance and liver retention of Feridex was 0.46 h and 60%, following administration of 4.8 mg Fe/kg Feridex. Atherosclerotic rabbits were administered 0.5 or 4.8 mg Fe/kg dosages of either fractionated Feridex or Feridex. MRI was performed at 1.5T over a 24-h time period postinjection. Perls and RAM-11 staining was performed to identify iron deposition. MRI showed a dose-dependent signal loss using conventional gradient echo (GRE) sequences following administration of fractionated Feridex. Even at low dose, significant signal loss was observed that correlated with histology. No signal attenuation or iron deposition was observed in the vessel wall of rabbits administered Feridex. Results of this study suggest that it may be possible to optimize USPIOs for intraplaque macrophage detection.
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Affiliation(s)
- Karen C Briley-Saebo
- Department of Radiology, Mount Sinai School of Medicine, New York, New York 10029-6574, USA.
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Ronald JA, Walcarius R, Robinson JF, Hegele RA, Rutt BK, Rogers KA. MRI of early- and late-stage arterial remodeling in a low-level cholesterol-fed rabbit model of atherosclerosis. J Magn Reson Imaging 2008; 26:1010-9. [PMID: 17896368 DOI: 10.1002/jmri.21113] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To monitor early- and late-stage arterial remodeling following low-level cholesterol (CH) feeding in rabbits using a standardized MRI protocol. MATERIALS AND METHODS New Zealand White rabbits were fed a CH diet (0.25% w/w) (n = 15) or normal chow (n = 6) and imaged either at 0, 2, 6, 8, and 11 months ("early-stage") or 12, 14, 16, 18, and 20 months ("late-stage"). T2-weighted fast-spin-echo images ( approximately 200 microm in-plane resolution) of aortic lesions were collected using either a 1.5 or 3.0T MR scanner interfaced with a customized surface RF coil. Luminal (LA), outer vessel wall boundary (OVBA), and vessel wall areas (VWA) were assessed. RESULTS Among CH-fed animals in the early-stage group, increased VWA associated with decreased OVBA and a more pronounced decrease in LA was first detectable at 8 months. These changes became more evident between 8 and 11 months. In the late-stage group, lesions continued to grow in response to CH-feeding, as VWA significantly increased at regular 2-month intervals. Beyond 16 months, signal intensity differences (reflecting increased lesion complexity) within the vessel wall were noted. CONCLUSION This often-overlooked rabbit model combined with customized MR technology holds tremendous promise for studying the natural progression, regression, and remodeling of atherosclerotic lesions.
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Affiliation(s)
- John A Ronald
- Department of Medical Biophysics, University of Western Ontario, London, ON, Canada
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Meding J, Urich M, Licha K, Reinhardt M, Misselwitz B, Fayad ZA, Weinmann HJ. Magnetic resonance imaging of atherosclerosis by targeting extracellular matrix deposition with Gadofluorine M. Contrast Media Mol Imaging 2008; 2:120-9. [PMID: 17557276 DOI: 10.1002/cmmi.137] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
As previously reported, Gadofluorine M-enhanced magnetic resonance imaging clearly demarcates atherosclerotic plaques from the normal vessel wall. To date, the underlying mechanism has remained unknown. Gadofluorine M is a gadolinium-containing macrocyclic contrast agent containing hydrophilic and hydrophobic moieties. To elucidate the mechanism of accumulation, fluorescently labeled and radioactively labeled derivates of Gadofluorine M were used to determine affinity and specificity of Gadofluorine M binding to blood serum and plaque components in vitro and for the distribution within the plaque of WHHL rabbits in vivo. Gadofluorine M binds to serum albumin, leading to a breakdown of micelles after intravenous injection. The affinity of Gadofluorine M to serum albumin is k(D) = 2 micromol/l. Gadofluorine then penetrates the atherosclerotic plaque while bound to albumin and then accumulates within the extracellular, fibrous parts of the plaque by binding to collagens, proteoglycans and tenascin, having the same affinity to these plaque constituents as to albumin. In contrast, weak binding was determined to LDL (k(D) = 2 mmol/l) and even no binding to hyaluronic acid. The driving force of binding and accumulation is the hydrophobic moiety of the molecules interacting with hydrophobic plaque materials. Thus, Gadofluorine M accumulates within the fibrous plaque or in the fibrous cap of a plaque containing high amounts of extracellular matrix components, but not in the lipid-rich areas. In combination with high-resolution MRI, Gadofluorine M might enable the detection of thin-cap fibroatheromas, also named the vulnerable plaque.
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Affiliation(s)
- Jörg Meding
- Research Laboratories of Bayer Schering Pharma AG, Berlin, Germany.
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8
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Abstract
PURPOSE To achieve a high spatial resolution in MR imaging that allows for clear visualization of anatomy and even histology and documentation of plaque morphology in in vitro samples from patients with advanced atherosclerosis. A further objective of our study was to evaluate whether T2-weighted high-resolution MR imaging can provide accurate classification of atherosclerotic plaque according to a modified American Heart Association classification. METHODS T2-weighted images of arteries were obtained in 13 in vitro specimens using a 3 T MR unit (Medspec 300 Avance/Bruker, Ettlingen, Germany) combined with a dedicated MR microscopy system. Measurement parameters were: T2-weighted sequences with TR 3.5 sec, TE 15-120 msec; field of view (FOV) 1.4 x 1.4; NEX 8; matrix 192; and slice thickness 600 microm. MR measurements were compared with corresponding histologic sections. RESULTS We achieved excellent spatial and contrast resolution in all specimens. We found high agreement between MR images and histology with regard to the morphology and extent of intimal proliferations in all but 2 specimens. We could differentiate fibrous caps and calcifications from lipid plaque components based on differences in signal intensity in order to differentiate hard and soft atheromatous plaques. Hard plaques with predominantly intimal calcifications were found in 7 specimens, and soft plaques with a cholesterol/lipid content in 5 cases. In all specimens, hemorrhage or thrombus formation, and fibrotic and hyalinized tissue could be detected on both MR imaging and histopathology. CONCLUSION High-resolution, high-field MR imaging of arterial walls demonstrates the morphologic features, volume, and extent of intimal proliferations with high spatial and contrast resolution in in vitro specimens and can differentiate hard and soft plaques.
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Affiliation(s)
- Johannes Sailer
- Department of Angiography and Interventional Radiology, University of Vienna, Vienna, Austria.
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Phan BAP, Chu B, Kerwin WS, Xu D, Yuan C, Hatsukami T, Zhao XQ. Effect of contrast enhancement on the measurement of carotid arterial lumen and wall volume using MRI. J Magn Reson Imaging 2006; 23:481-5. [PMID: 16523478 DOI: 10.1002/jmri.20540] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To investigate whether gadolinium (Gd)-based contrast enhancement (CE) affects high-resolution magnetic resonance imaging (MRI) measurements of carotid arterial wall volume. MATERIALS AND METHODS The common carotid artery (CCA), bifurcation, and internal carotid artery (ICA) of 50 consecutive patients were imaged using 1.5T MRI. T1-weighted (T1W) images were obtained before and after Gd administration. Pre- and post-CE measurements were compared among different arterial locations of the CCA, bifurcation, and ICA, and among different atherosclerotic lesion types. RESULTS In comparison to pre-CE T1W images, post-CE images showed an increase in the apparent wall volume measurement of 28.2% (108.7 mm3 vs. 84.7 mm3, P < 0.001). The post-CE measurement increases in wall volume for the CCA, bifurcation, and ICA were 26.7%, 29.2%, and 28.0%, respectively. CONCLUSION Gd CE causes a significant increase in the apparent volume of the carotid wall throughout multiple carotid artery locations, which may be associated with improved visibility or neovascularization.
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Affiliation(s)
- Binh An P Phan
- Department of Medicine, University of Washington, Seattle, Washington 98103-8771, USA.
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10
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Abstract
AIM To evaluate the potential role of carotid artery atherosclerosis plaque magnetic resonance (MR) microimaging as magnetic resonance imaging (MRI) marker, ex vivo MR images were acquired at optimized parameters on 9.4T Bruker animal imager for occluded tissue resected by carotid endarterectomy (CEA) and corresponding histopathological analysis was made. METHODS AND MATERIALS For imaging, CEA tissues of size 2-6 cm long and 0.5-1.5 cm wide, were transferred to 15 ml co-polymer laboratory culture tubes containing either 10% formalin in phosphate buffered saline (PBS) or in 50% glycerol in PBS. Imaging protocol was set at TE=30 ms, TR=1.5 s, matrix size=265 x 512, NEX=128, slice thickness=1 mm and in-plane resolution=0.1 mm for total sample size 2.5 cm. Soon after imaging done, carotid artery tissues were cut into 5-mm segments and processed for histological section for successive 5-micrometer slices. To compare morphology of 5 mum thin CEA section with that of 1 mm MR slices, registration was obtained between histologic sections and MR slices. Contrast and magnetic resonance relaxation characteristics were analyzed. RESULTS Total carotid artery area computed by MR imaging was correlated with areas determined from histologic sections (r(2)=0.989, p=0.0001). For the lumen area, the correlation between MR images and histologic area was (r(2)=0.942, p=0.0001). Relaxation times and T(2) parametric images of different plaque components were determinant for contrast resolution. Scan parameters were optimized for fibrous cap and atheroma. Scan parameters were characteristic for comparison at 1.5T and 9.4T MR imagers. CONCLUSION The observed correlation validated MR microimaging to assess morphological features of carotid artery plaques and contrast resolution highlighted the potential of in vivo MR imaging as non-invasive MRI marker to monitor carotid artery plaque morphometry and plaque composition.
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Affiliation(s)
- Rakesh Sharma
- Atherosclerosis Division, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
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Abstract
The survival of fat grafts depends on many factors, 1 of the major being early revascularization. Early studies showed that adipose tissue has a low tolerance to ischemia. Some methods have been described to increase the tolerance of adipose tissue to ischemia. This study was designed to compare volume maintenance of the transplanted fat graft in different recipient sites of the rabbit face. Three groups of 5 New Zealand white rabbits were studied. Fat grafts harvested from the right inguinal fat pad were transplanted to the buccomandibular area of the rabbit's face. Three different recipient sites (subcutaneous, supramuscular, and submuscular) were dissected on each side of the face, and groups were formulated based on this difference of recipient sites. Morphometric, as well as histopathologic, analyses were done, and the results revealed a statistically significant increase of fat graft survival in supramuscular layer (81.95% +/- 4.40%) than in subcutaneous (41.62% +/- 3.29%) and submuscular layer (37.31% +/- 5.77%) (P<0.05). This study demonstrates that selection of an "appropriate recipient site" should enhance ultimate fat-graft survival.
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Affiliation(s)
- Ercan Karacaoglu
- Brown University, School of Medicine, Rhode Island Hospital, Providence, RI, USA.
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Affiliation(s)
- W Yong Kim
- MR-Center, Institute of Clinical Medicine, Aarhus University Hospital, Skejby Sygehus, Denmark.
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13
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Abstract
OBJETIVO: Identificar ateromas carotídeos em coronariopatas com indicação de terapia cirúrgica. Avaliar o grau de estenose das artérias carótidas internas por meio de ultra-sonografia com Doppler colorido (UDC) e angiografia por ressonância magnética (ARM). Comparar a ecogenicidade das placas visualizadas pela ultra-sonografia (US), com a intensidade de sinal nos exames de ressonância magnética (RM). Avaliar a qualidade de imagens e confiabilidade interobservadores nos exames de RM. MATERIAIS E MÉTODOS: Estudo prospectivo em 50 pacientes. Utilizamos US e RM em seqüências ponderadas em T1 e T2, ambas pelas técnicas "black-blood" (BB) e "fat sat black-blood" (FSBB), e ARM 3D TOF ("time-of-flight'') com e sem contraste paramagnético. RESULTADOS: Do total de 100 segmentos, 81% apresentaram estenose pela US. Em 72 placas com ecogenicidade tipo 4 houve aumento da intensidade de sinal em 59,7% em T1-BB, 65,3% em T1-FSBB, 62,5% em T2-BB e 66,7% em T2-FSBB. Nas placas tipo 2 houve aumento da intensidade de sinal em 71,4% em T1-BB e T1-FSBB, 85,7% em T2-BB e 71,4% em T2-FSBB. Nas placas tipo 1 houve aumento da intensidade de sinal em 50,0% em T1 e T2. Em 19 segmentos a US foi considerada normal. Quando estes segmentos foram avaliados pela RM, houve aumento da intensidade de sinal em 47,4% em T1-BB, 57,9% em T1-FSBB e 52,6% em T2-BB e T2-FSBB. CONCLUSÃO: Houve alta incidência de aterosclerose carotídea. Houve reprodutibilidade marginal na associação entre o grau de estenose visualizado pela UDC e ARM. Não houve correlação entre os tipos de ecogenicidade das placas visualizadas pela US com as alterações de intensidade de sinal pela RM. A qualidade de imagens dos exames de RM foi considerada ótima em T1 e T2 e muito boa em 3D TOF (axial). A qualidade de imagem dos exames de ARM foi excelente. Notou-se ótima reprodutibilidade interobservadores, com valores de índice kappa acima de 0,71.
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Trogan E, Fayad ZA, Itskovich VV, Aguinaldo JGS, Mani V, Fallon JT, Chereshnev I, Fisher EA. Serial Studies of Mouse Atherosclerosis by In Vivo Magnetic Resonance Imaging Detect Lesion Regression After Correction of Dyslipidemia. Arterioscler Thromb Vasc Biol 2004; 24:1714-9. [PMID: 15256400 DOI: 10.1161/01.atv.0000139313.69015.1c] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective—
We determined the effects of sustained normocholesterolemia on advanced mouse atherosclerosis and whether changes in plaque size and composition can be detected noninvasively by MRI.
Methods and Results—
Aortic arch segments containing advanced lesions from apolipoprotein E–deficient (apoE−/−) mice (total cholesterol 1281±97 mg/dL) were transplanted into syngeneic wild-type (WT; 111±11 mg/dL) or apoE−/− (702±74 mg/dL) recipient mice on chow diet. Mice underwent serial MRI at 3, 5, 7, and 9 weeks after transplantation. Compared with 3 weeks, correction of dyslipidemia in WT recipient mice resulted in a monotonic decrease (regression) in arterial wall volume, whereas in apoE−/− recipient mice, further plaque progression was noted (
P
<0.05). MRI and histological measurements were closely correlated (
R
=0.937). The lesional content of macrophages decreased >90% (
P
<0.001), and smooth muscle cells increased in the WT recipient mice. In vivo T
1
-, T
2
-, and proton density–weighted images of the mouse thoracic aorta differentiated intraplaque lipid and collagen.
Conclusions—
Plaque changes can be noninvasively monitored by serial in vivo MRI of a mouse regression model. Our ability to image the thoracic aorta and perform in vivo plaque characterization will further enhance atherosclerosis studies.
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Affiliation(s)
- Eugene Trogan
- Zena and Michael A. Wiener Cardiovascular Institute, Mount Sinai School of Medicine, New York, NY, USA
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15
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Chaabane L, Soulas EC, Contard F, Salah A, Guerrier D, Briguet A, Douek P. High-resolution magnetic resonance imaging at 2 Tesla: potential for atherosclerotic lesions exploration in the apolipoprotein E knockout mouse. Invest Radiol 2003; 38:532-8. [PMID: 12874520 DOI: 10.1097/01.rli.0000067491.31978.1c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
INTRODUCTION The aim of the present study was to evaluate the potential of high-resolution MRI at 2 Tesla (T) for direct noninvasive imaging of the aortic wall in a mouse model of atherosclerosis. MATERIAL AND METHODS A specific mouse antenna was developed and sequence parameters were adjusted. T(1)- and T2-weighted images of abdominal aorta were obtained at 2 T with a spatial resolution of 86 x 86 x 800 microm3 in vivo. With a dedicated small coil, ex vivo MRI of the aorta was performed with a spatial resolution of 54 x 54 x 520 microm3. RESULTS In vivo, the aortic wall was clearly defined on T(2)-weighted images in 15 of 16 mice: along the aorta the lumen circumference ranged from 1.07 to 3.61 mm and mean wall thickness from 0.11 to 0.67 mm. In vivo measurements of plaque distribution were confirmed by ex vivo MR imaging and by histology, with a good correlation with histology regarding lumen circumference (r = 0.94) and wall thickness (r = 0.97). CONCLUSION Magnetic resonance imaging at 2 T to analyze in vivo atherosclerotic lesions in mice is possible with a spatial resolution of 86 x 86 x 800 microm3 and thus can be used for noninvasive follow-up in evaluation of new drugs.
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Affiliation(s)
- Linda Chaabane
- Laboratoire de RMN, UMR 5012 CNRS, UCB-CPE, Lyon, France.
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16
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Hockings PD, Roberts T, Galloway GJ, Reid DG, Harris DA, Vidgeon-Hart M, Groot PHE, Suckling KE, Benson GM. Repeated Three-Dimensional Magnetic Resonance Imaging of Atherosclerosis Development in Innominate Arteries of Low-Density Lipoprotein Receptor-Knockout Mice. Circulation 2002; 106:1716-21. [PMID: 12270868 DOI: 10.1161/01.cir.0000030188.50326.8d] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
In vivo methods to evaluate the size and composition of atherosclerotic lesions in animal models of atherosclerosis would assist in the testing of antiatherosclerotic drugs. We have developed an MRI method of detecting atherosclerotic plaque in the major vessels at the base of the heart in low-density lipoprotein (LDL) receptor-knockout (LDLR
−/−
) mice on a high-fat diet.
Methods and Results—
Three-dimensional fast spin-echo magnetic resonance images were acquired at 7 T by use of cardiac and respiratory triggering, with ≈140-μm isotropic resolution, over 30 minutes. Comparison of normal and fat-suppressed images from female LDLR
−/−
mice 1 week before and 8 and 12 weeks after the transfer to a high-fat diet allowed visualization and quantification of plaque development in the innominate artery in vivo. Plaque mean cross-sectional area was significantly greater at week 12 in the LDLR
−/−
mice (0.14±0.086 mm
2
[mean±SD]) than in wild-type control mice on a normal diet (0.017±0.031 mm
2
,
P
<0.01). In the LDLR
−/−
mice, but not control mice, increase in plaque burden at week 12 relative to week 1 was also highly significant (
P
=0.001). Lumen cross section was not significantly different between time points or groups. MRI and histological assessments of plaque size were closely correlated (
R
=0.8). The lumen of proximal coronary arteries could also be visualized.
Conclusions—
This is the first report of in vivo detection of aortic arch atherosclerosis in any animal model. The method could significantly assist rapid evaluation of experimental antiatherosclerotic therapies.
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17
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Ochiai R, Kisanuki A, Asada Y, Asato M, Tamura S, Sumiyoshi A. Intravascular ultrasound imaging in the assessment of atherosclerotic plaques in rabbit abdominal aorta: comparison with histologic findings. Invest Radiol 2002; 37:309-13. [PMID: 12021586 DOI: 10.1097/00004424-200206000-00001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
RATIONALE AND OBJECTIVES To examine the correlation between the echogenicity and the components of atherosclerotic plaques in rabbit. METHODS The atherosclerotic plaque formation in the abdominal aortas of hyperlipidemic or normolipidemic rabbits was stimulated by inserting polyethylene tubing. Intravascular ultrasound (30-MHz, 4.5 F catheter) investigation was performed at locations in the vessel. The intravascular ultrasound images of the plaques were evaluated and compared with the histologic findings. RESULTS Ultrasound images delineated areas showing hyperechoic or hypoechoic ultrasound beams in the plaques. Histologic studies revealed that the hyperechoic areas were closely associated with a dense fibrous extracellular matrix, whereas the hypoechoic areas corresponded to lesions showing a marked accumulation of foamy macrophages or proteoglycan-rich loose myxoid extracellular matrix with smooth muscle cell proliferation. CONCLUSION A good correlation between ultrasound images and histologic features was observed. These results suggest that intravascular ultrasound imaging could provide useful information for assessing the tissue characteristics of atherosclerotic lesions.
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Affiliation(s)
- Reiji Ochiai
- Department of Radiology, Miyazaki Medical College, Kiyotake, Japan.
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18
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Helft G, Worthley SG, Fuster V, Fayad ZA, Zaman AG, Corti R, Fallon JT, Badimon JJ. Progression and regression of atherosclerotic lesions: monitoring with serial noninvasive magnetic resonance imaging. Circulation 2002; 105:993-8. [PMID: 11864931 DOI: 10.1161/hc0802.104325] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Modification or stabilization of atherosclerotic plaques has been proposed as the mechanism responsible for the beneficial clinical effect of lipid-lowering therapies. An imaging modality able to quantify atherosclerotic plaque composition could potentially allow not only the identification of these vulnerable atherosclerotic lesions, but also monitoring of the effects of therapeutic interventions on plaque composition. Our aim was to monitor changes in burden and composition of atherosclerotic plaques in a rabbit model of complex atherosclerosis using serial noninvasive magnetic resonance imaging (MRI). METHODS AND RESULTS Aortic atherosclerotic lesions were induced in rabbits and the animals randomized to continue an atherogenic diet (atherosclerosis progression) or resume normal chow (atherosclerosis regression) for 6 months. MRI of the aorta was performed at 3 time points in each rabbit, as follows: baseline, after atherosclerosis induction (9 months old), and after atherosclerosis regression or progression (15 months old). Histopathologic correlation with MRI was performed. There was a significant (P<0.0001) reduction in atherosclerotic burden in the regression group, and an increase in the progression group. There was a significant (P<0.001) reduction in the lipidic component of plaques in the regression group, and an increase in the progression group. A small, nonsignificant increase in the fibrotic plaque components was noted in the regression group, but a significant decrease in the fibrotic composition of lesions in the progression group. A significant correlation (P<0.001) was found between MRI and histopathology for atherosclerotic burden and plaque composition. CONCLUSIONS These findings indicate that serial noninvasive MRI can monitor changes in atherosclerotic plaque composition under conditions of atherosclerotic progression and regression.
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Affiliation(s)
- Gérard Helft
- Zena and Michael A. Wiener Cardiovascular Institute, Mount Sinai Medical Center, New York, NY 10029-6574, USA
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19
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Zhang S, Hatsukami TS, Polissar NL, Han C, Yuan C. Comparison of carotid vessel wall area measurements using three different contrast-weighted black blood MR imaging techniques. Magn Reson Imaging 2001; 19:795-802. [PMID: 11551719 DOI: 10.1016/s0730-725x(01)00408-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Measuring carotid artery plaque burden from MRI is a reliable method for monitoring regression and progression of atherosclerosis. However, to measure all available images would be very time consuming, and in practice the image quality (IQ) of these images may be inconsistent, which can directly impact the quality of measurement. It is hypothesized that if IQ is comparable among different contrast weighted images, then carotid artery area measurements obtained from different contrast images of the same location will produce identical results. To test this, T1, proton density and T2 weighted images were acquired from ten patients (51 +/- 7 years old). Carotid lumen and vessel wall area was measured using a custom designed software program. The results showed strong agreement evidenced with only small differences on both lumen (mean: 40.5 mm(2)) and wall (mean: 52.6 mm(2)) area measurement among different weighted images. The maximum absolute mean differences are less than 2.7 mm(2) and 4.4 mm(2), and 90(th) percentile of the absolute differences are 5.6 mm(2) and 8.2 mm(2) respectively. In conclusion, different contrast weighted images with high and comparable IQ will yield similar results in lumen and vessel wall area measurement. At each matched location, it is recommended that the image with the highest IQ be used for area measurement.
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Affiliation(s)
- S Zhang
- Department of Radiology, Cardiovascular Institute and Fu Wai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College 100037, Beijing, China.
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20
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Abstract
Magnetic resonance imaging (MRI) of carotid plaque has undergone significant improvements in the last decade. Early studies utilizing ex vivo specimens and spin-echo or fast spin-echo imaging led to the conclusion that T2 weighting is the best single contrast to characterize carotid plaque morphology. On these images, the fibrous plaque appears bright and the lipid core is dark; thrombus can have variable intensity. There can be an overlap in T2-weighted signal intensities among the various plaque components, which can be partially offset by the use of multispectral analysis of multiple contrast images. With improvements in coil design, sequence design, and main field and gradient capabilities, accurate in vivo differentiation and measurement of these various carotid plaque components should be possible in 3 to 5 years. Ex vivo and in vivo studies have yielded high-resolution measurements of the complex three-dimensional lumen geometry, which are being used to predict hemodynamic forces acting on the lumenal surface. Carotid plaque burden can be accurately measured in vivo today; ongoing longitudinal studies should lead to a better understanding of the relationship between plaque burden and the risk of thromboembolic complications, as well as the effect of diet and drug therapy in hyperlipidemic patients. With these developments in place or soon to be available, MRI of the diseased carotid artery wall may prove to be even more important than magnetic resonance angiography.
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Affiliation(s)
- J K Demarco
- University Radiology Group, University of Medicine and Dentistry of New Jersey, Laurie Imaging Center, New Brunswick 08901, USA
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21
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Abstract
The study of atherosclerotic disease during its natural history and after therapeutic intervention may enhance our understanding of the progression and regression of this disease and will aid in selecting the appropriate medical treatments or surgical interventions. Several invasive and non-invasive imaging techniques are available to assess atherosclerotic disease vessels. Most of these techniques are strong in identifying the morphological features of the disease such as lumenal diameter and stenosis or wall thickness, and in some cases provide an assessment of the relative risk associated with the atherosclerotic disease. However, none of these techniques can fully characterize the composition of the atherosclerotic plaque in the vessel wall and therefore are incapable of identifying the vulnerable plaques. High-resolution, multi-contrast, magnetic resonance (MR) can non-invasively image vulnerable plaques and characterize plaques in terms of lipid and fibrous content and identify the presence of thrombus or calcium. Application of MR imaging opens up whole new areas for diagnosis, prevention, and treatment of atherosclerosis.
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Affiliation(s)
- Z A Fayad
- The Zena and Michael A. Wiener Cardiovascular Institute, and Department of Radiology, Mount Sinai School of Medicine, New York, NY 10029, USA.
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22
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Serfaty JM, Chaabane L, Tabib A, Chevallier JM, Briguet A, Douek PC. Atherosclerotic plaques: classification and characterization with T2-weighted high-spatial-resolution MR imaging-- an in vitro study. Radiology 2001; 219:403-10. [PMID: 11323464 DOI: 10.1148/radiology.219.2.r01ma15403] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate if T2-weighted high-spatial-resolution magnetic resonance (MR) imaging (117 microm per pixel) can help accurate classification of atherosclerotic plaques. MATERIALS AND METHODS Thirty human arteries and 11 carotid endarterectomy specimens from 31 patients underwent T2-weighted MR imaging (2-T magnet; repetition time, 2,000 msec; echo time, 50 msec) at room temperature. After imaging, Bouin fixative was used to fix 26 arteries, and the other 15 arteries were fixed by means of freezing. Specimens were stained with hematoxylin-eosin and safranin or Sudan lipid stain. MR images and histologic slices were classified independently by two radiologists and a pathologist, respectively, on the basis of the American Heart Association classification. RESULTS Results with MR imaging were the following: type I-II plaques, sensitivity of 67% and specificity of 100%; type IV-Va plaques, sensitivity of 74% and specificity of 85%; type Vb plaques, sensitivity of 90% and specificity of 100%; type Vc plaques, sensitivity of 80% and specificity of 90%. No type III plaque was diagnosed in the study. The overall kappa value was 0.68. CONCLUSION High-spatial-resolution MR imaging with T2 weighting alone can help accurate classification of fibrocalcic plaques (type Vb), but it is subject to limitations for the classification and analysis of other types of atherosclerotic plaques.
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Affiliation(s)
- J M Serfaty
- Laboratoire de Résonance Magnétique Nuclèaire Unité Mixte de Recherche, Villeurbanne, France.
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23
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Helft G, Worthley SG, Fuster V, Zaman AG, Schechter C, Osende JI, Rodriguez OJ, Fayad ZA, Fallon JT, Badimon JJ. Atherosclerotic aortic component quantification by noninvasive magnetic resonance imaging: an in vivo study in rabbits. J Am Coll Cardiol 2001; 37:1149-54. [PMID: 11263622 DOI: 10.1016/s0735-1097(01)01141-x] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES We sought to demonstrate the ability that noninvasive in vivo magnetic resonance imaging (MRI) has to quantify the different components within atherosclerotic plaque. BACKGROUND Atherosclerotic plaque composition plays a critical role in both lesion stability and subsequent thrombogenicity. Noninvasive MRI is a promising tool for the characterization of plaque composition. METHOD Thoracic and abdominal aortic atherosclerotic lesions were induced in rabbits (n = 5). Nine months later, MRI was performed in a 1.5T system. Fast spin-echo sequences (proton density-weighted and T2-weighted [T2W] images) were obtained (in-plane resolution: 350 x 350 microns, slice thickness: 3 mm). Magnetic resonance images were correlated with matched histopathological sections (n = 108). RESULTS A significant correlation (p < 0.001) was observed for mean wall thickness and vessel wall area between MRI and histopathology (r = 0.87 and r = 0.85, respectively). The correlation was also present on subanalysis of the thoracic and upper part of the abdominal aorta, susceptible to respiratory motion artifacts. There was a significant correlation for plaque composition (p < 0.05) between MRI and histopathology for the analysis of lipidic (low signal on T2W, r = 0.81) and fibrous (high signal on T2W, r = 0.86) areas with Oil Red O staining. T2-weighted images showed greater contrast than proton density-weighted between these different components of the plaques as assessed by signal intensity ratio analysis with the mean difference in signal ratios of 0.47 (S.E. 0.012, adjusted for clustering of observations within lesions) being significantly different from 0 (t1 = 39.1, p = 0.016). CONCLUSIONS In vivo noninvasive high resolution MRI accurately quantifies fibrotic and lipidic components of atherosclerosis in this model. This may permit the serial analysis of therapeutic strategies on atherosclerotic plaque stabilization.
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Affiliation(s)
- G Helft
- Cardiovascular Biology Research Laboratory, Zena and Michael A. Wiener Cardiovascular Institute, Mount Sinai Medical Center, New York, New York 10029-6574, USA
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24
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Ono K, Watanabe S, Daimon Y, Sakurada H, Urano M, Sun K, Hijikata Y, Inoue T, Masuda Y. Diagnosis of carotid artery atheroma by magnetic resonance imaging. Jpn Circ J 2001; 65:139-44. [PMID: 11266184 DOI: 10.1253/jcj.65.139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Atheroma appears as a very low signal intensity area on 2-dimensional time-of-flight (TOF) magnetic resonance (MR) images, and its components have various signal intensities on spin-echo (SE) images. The present study investigated atheroma of the carotid arteries in 37 subjects with risk factors (63+/-10 years of age; 19 men) by magnetic resonance imaging (MRI). On 2-dimensional (2D) TOF images, the carotid arteries were clearly demonstrated in all cases and atheroma was detected in 23 patients. The most common location of atheroma was at the origin of the internal carotid artery. There was vascular remodeling in all patients with atheroma. 2D-TOF images showed 97% agreement with ultrasonography. SE images clearly demonstrated atheroma in all 23 patients with atheroma. All patients with atheroma showing high signal intensity on T1-weighted images had hyperlipidemia. These findings indicate that the 2D-TOF imaging method is useful for detecting atheroma and SE-images are useful for its characterization.
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Affiliation(s)
- K Ono
- Third Department of Internal Medicine, Chiba University School of Medicine, Chiba City, Japan
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25
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Abstract
-This review focuses on the regression of atherosclerosis in humans and experimental animals. It highlights the difficulties to determine unequivocally whether with a given therapeutic intervention, such as diet, drugs, or apheresis, the progression of lesions was curtailed or bona fide regression of atherosclerotic lesions was achieved. It seems appropriate to mention that 2 very different ways to measure regression were used in experimental animals and in humans. Regression in animals was determined mainly in the aorta or coronary arteries isolated at post mortem, and the criteria used were degree of sudanophilia and/or aortic wall thickness and cellular composition or cholesterol content. In humans, the evaluation of regression relied mainly on quantitative coronary angiography. The literature of the past decade is reviewed selectively but not exhaustively, and in some instances, a brief historical overview is given.
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Affiliation(s)
- Y Stein
- Lipid Research Laboratory, Division of Medicine, Hadassah University Hospital, Jerusalem, Israel.
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26
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Rudin M, Allegrini PR, Beckmann N, Ekatodramis D, Laurent D. In-vivo cardiac studies in animals using magnetic resonance techniques: experimental aspects and MR readouts. MAGMA 2000; 11:33-5. [PMID: 11186979 DOI: 10.1007/bf02678487] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- M Rudin
- Core Technologies Area, Analytics and Imaging Science Unit, Novartis Pharma, Basel, Switzerland.
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27
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Heverhagen JT, Kalinowski M, Schwarz U, Klose KJ, Alfke H. Quantitative human in vivo evaluation of high resolution MRI for vessel wall morphometry after percutaneous transluminal angioplasty. Magn Reson Imaging 2000; 18:985-9. [PMID: 11121702 DOI: 10.1016/s0730-725x(00)00187-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Visualization of the vessel wall after transluminal angioplasty is important to monitor the restenosis progress. Intravascular ultrasound proved its capabilities as an invasive procedure in many studies. The aim of this study was to evaluate the feasibility of high-resolution MRI as a non-invasive tool for follow-up after PTA. High-resolution magnetic resonance images (pixel size: 0.49 * 0.49 mm(2)) were acquired on a 1.0 T clinical scanner. Morphometry was conducted after conversion of DICOM images into TIFF format using ScionImage on a PC. In-vitro studies using a polyvinylchloride tube were evaluated by two independent investigators. Goldstandard was a caliper rule and direct radiography. Five patients were monitored before and 24 h, six weeks, three months and six months after PTA. In vivo measurements promised a good concordance for both investigators for area as well as for diameter measurements. Area measurements showed correlations up to r = 0.86 (p < 0.001) whereas the correlations of diameters were slightly inferior (r between 0.58 and 0.84; p < 0.005). Relocation of the same slice position in the follow up studies could be guaranteed using anatomic landmarks in the images. As a non-invasive tool to assess restenosis after PTA high-resolution MRI promises to be a reproducible technique. It is easy to identify the same vascular region in different studies due to neighboring anatomic landmarks. Progression of disease as well as success of pharmacologic treatment to prevent restenosis may be monitored.
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Affiliation(s)
- J T Heverhagen
- Dept. of Diagnostic Radiology, University Hospital, Philipps University, Marburg, Germany.
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28
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Abstract
The study of atherosclerotic disease during its natural history and after therapeutic intervention will enhance our understanding of the progression and regression of this disease and will aid in selecting the appropriate medical treatments or surgical interventions. Several invasive and noninvasive imaging techniques are available to assess atherosclerotic vessels. Most of these techniques are strong in identifying the morphological features of the disease, such as lumenal diameter and stenosis or wall thickness, and in some cases provide an assessment of the relative risk associated with the atherosclerosis. However, none of these techniques can fully characterize the composition of the atherosclerotic plaque in the vessel wall and, therefore, are incapable of identifying the vulnerable plaques. High-resolution, multi-contrast, magnetic resonance (MR) can non-invasively image vulnerable plaques, characterize plaques in terms of lipid and fibrous content, and identify the presence of thrombus or calcium. Application of MR imaging opens up whole new areas for diagnosis, prevention, and treatment (e.g., lipid-lowering drug regimens) of atherosclerosis.
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Affiliation(s)
- Z A Fayad
- Zena and Michael A. Wiener Cardiovascular Institute, New York, New York, USA.
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29
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Abstract
Cryogenically cooled conventional surface coils are shown to provide significant signal-to-noise ratio (SNR) gains for MR micro imaging of tissue structure in vivo. Measurements are described which employ a simple, all-polyvinyl chloride (PVC) vacuum dewar capable of maintaining a bath of liquid nitrogen around the coil, within 5 mm of the tissue to be imaged. Images acquired in vivo at 64 MHz with a 2-cm diameter copper coil cooled to 77 K demonstrated a gain in SNR of approximately 2.7 +/- 0.3 relative to those obtained with the same coil at room temperature under otherwise identical conditions. This increase is consistent with the reduction in coil resistance and the minor contribution to overall resistance from the imaging object. The performance of the coil is illustrated with images from the human finger and rabbit eye and potential applications are discussed.
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Affiliation(s)
- A C Wright
- Department of Radiology, Hosptial of the University of Pennsylvania, Philadelphia 19104, USA.
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30
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Beckmann N, Stirnimann R, Bochelen D. High-resolution magnetic resonance angiography of the mouse brain: application to murine focal cerebral ischemia models. J Magn Reson 1999; 140:442-450. [PMID: 10497049 DOI: 10.1006/jmre.1999.1864] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Three-dimensional time-of-flight high-resolution magnetic resonance angiography was applied to visualize the cerebral vasculature of the mouse brain. In normal mice, angiograms of good quality, showing the essential details of the arterial cerebrovascular anatomy, could be obtained in only 2.5 min without the use of contrast agents. Signals from slowly flowing blood, e.g., in veins, could also be detected after administration of a blood pool contrast agent. The technique was applied to mouse models of permanent and transient brain ischemia, involving the occlusion of the middle cerebral artery. High-resolution magnetic resonance angiography proved to be a very useful tool for verifying the success of the occlusion in these models.
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Affiliation(s)
- N Beckmann
- Core Technologies Area, Novartis Pharma Inc., Basel, CH-4002, Switzerland
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31
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Abstract
We describe and discuss the application of three-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA) to visualize non-invasively the cerebral vasculature of the rat. MR angiograms of healthy spontaneously hypertensive rats were obtained without the use of contrast agents. Total imaging time ranged from 1 to 50 min for a 3D data set. The influences of the data matrix and the inflow delay on the image quality and the total imaging time are assessed and discussed. Varying the inflow delay yielded in addition semiquantitative information on hemodynamics. The method was applied to obtain angiograms in rat models of permanent and temporal middle cerebral artery occlusion. Occlusion and reopening of the vessel could easily be verified by MRA. However, after reperfusion a slight reduction in blood flow was observed.
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Affiliation(s)
- T Reese
- Core Technology, Novartis Pharma Ltd, Basel, Switzerland.
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32
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Hänni M, Lekka-Banos I, Nilsson S, Häggroth L, Smedby O. Quantitation of atherosclerosis by magnetic resonance imaging and 3-D morphology operators. Magn Reson Imaging 1999; 17:585-91. [PMID: 10231185 DOI: 10.1016/s0730-725x(98)00195-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The objective was to ascertain whether MRI and image processing can be used to quantify atherosclerosis by measuring wall thickness in rabbit aorta. The abdominal aortas of 2 healthy and 5 atherosclerotic rabbits were examined with a gradient-echo inflow angiography sequence (2DI) and a proton density weighted turbo-spin-echo sequence (PDW). Using thresholding by four observers and 3D morphology operators, segmentation of the artery and vein lumina was performed from the 2DI sequence, and of surrounding fat and muscle from the PDW sequence. Remaining voxels adjacent to the aortic lumen were classified as vessel wall. By measuring the vessel wall volume and the lumen volume, the wall percentage was calculated. The values were significantly higher for the diseased animals than for unaffected individuals (p < 0.01). It is concluded that aortic wall thickening in atherosclerotic rabbits can be measured quantitatively by using MRI combined with 3D morphology image processing operators.
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Affiliation(s)
- M Hänni
- Department of Diagnostic Radiology, Uppsala University, Sweden.
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33
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Abstract
Quantitative measurements of the blood vessel wall area may provide useful information of atherosclerotic plaque burden, progression and/or regression. Magnetic resonance imaging is a promising technique for identifying both luminal and outer wall boundaries of the human blood vessels. Currently these boundaries are primarily defined manually, a process viewed as labor intensive and subject to significant operator bias. Fully automated post-processing techniques used for identifying the lumen and wall boundaries, on the other hand, are also problematic due to the complexity of signal features in the vicinity of the blood vessels. The goals of this study were to develop a robust, automated closed contour edge detection algorithm, apply this algorithm to high resolution human carotid artery images, and assess its accuracy, and reproducibility. Our algorithm has proven to be sensitive to various contrast situations and is reasonably accurate and highly reproducible.
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Affiliation(s)
- C Yuan
- Department of Radiology, University of Washington, Seattle 98195, USA.
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34
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35
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Manninen HI, Vanninen RL, Laitinen M, Räsänen H, Vainio P, Luoma JS, Pakkanen T, Tulla H, Ylä-Herttuala S. Intravascular ultrasound and magnetic resonance imaging in the assessment of atherosclerotic lesions in rabbit aorta. Correlation to histopathologic findings. Invest Radiol 1998; 33:464-71. [PMID: 9704286 DOI: 10.1097/00004424-199808000-00007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
RATIONALE AND OBJECTIVES The authors compare the usefulness of intravascular ultrasound (IVUS) and magnetic resonance imaging (MRI) for quantitation of atherosclerosis in hyperlipidemic rabbits, correlated with histopathology. METHODS Magnetic resonance imaging with T1- and T2-weighted spin echo sequences and three-dimensional time-of-flight MR angiography of the abdominal aorta was performed on seven rabbits using a 1.5 T MR imager and a standard head coil. X-ray angiography and IVUS examination (3.5 F/30 MHz imaging catheter) was performed via carotid artery access. RESULTS Time-of-flight MR angiography source images provided the best resolution and plaque-lumen contrast in visual comparison between the different MRI sequences. Intra- and interobserver reproducibilities of the lesion thickness and area measurements were similar in IVUS and MRI (Pearson correlations 0.52-0.97; P < 0.01). The measurements from IVUS and MRI correlated closely with each other as well as with those made from histopathologic specimens (Pearson correlations 0.50-0.79; P < 0.001). The measurements from IVUS were somewhat more accurate than those made from MRI. CONCLUSIONS Both MRI and IVUS with clinically available imaging equipments are feasible and accurate for the quantitation of experimental atherosclerosis of rabbit aorta.
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Affiliation(s)
- H I Manninen
- Department of Clinical Radiology, Kuopio University Hospital, University of Kuopio, Finland
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Abstract
Cardiac-gated black blood MRI of the carotid artery bifurcation in normal human subjects shows signal within the lumen suggesting wall thickening or atherosclerotic plaque. This signal was believed to be artifactual, arising from complex flow patterns present at the carotid bifurcation. Computer simulation of the hemodynamics and black blood multislice image acquisition in a model of the carotid bifurcation showed that these artifacts arise from spins recovering their signal within the slow, recirculating flow of the carotid bulb. The computed hemodynamics also suggested that these artifacts could be minimized or eliminated entirely by gating the acquisition of slices in the most artifact-prone region of the carotid bulb within a 250-ms window after peak systole. Application of these predictions to studies of normal volunteers showed that, in most cases, these flow artifacts in black blood MRI can be eliminated simply by altering the phase of the cardiac cycle to which the image acquisition is gated. The observation that the size and placement of the saturation slabs had little effect on these artifacts suggested that, in those cases in which recirculation persists throughout the cardiac cycle, either inversion-recovery or presaturation within the bulb itself would be required to suppress them.
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Affiliation(s)
- D A Steinman
- John P. Robarts Research Institute, London, Ontario, Canada
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Kaneko E, Yuan C, Skinner MP, Raines EW, Ross R. Serial magnetic resonance imaging of experimental atherosclerosis allows visualization of lesion characteristics and lesion progression in vivo. Ann N Y Acad Sci 1997; 811:245-52; discussion 252-4. [PMID: 9186602 DOI: 10.1111/j.1749-6632.1997.tb52006.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- E Kaneko
- Department of Pathology, University of Washington School of Medicine, Seattle 98195-7470, USA
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Ford JC, Shlansky-Goldberg RD, Golden M. MR microscopy of the arterial wall in an experimental model of atherosclerosis: preliminary results. J Vasc Interv Radiol 1997; 8:93-9. [PMID: 9025046 DOI: 10.1016/s1051-0443(97)70522-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
PURPOSE To obtain images of the arterial lumen and wall in a rabbit model of atherosclerosis with use of high-resolution magnetic resonance (MR) imaging to follow morphologic changes during the induction of atherosclerosis and, hence, develop a non-invasive tool to investigate restenosis. MATERIALS AND METHODS In vivo microscopic MR images of rabbit aorta were acquired after balloon injury. Measurements of wall and lumen diameter from MR images area were compared with measurements obtained from histologic and angiographic examination. RESULTS Injured rabbits exhibited an obvious thickening of the arterial wall, accompanied by an increased wall conspicuity, probably due to increases in T2. Quantitative MR morphometry corresponded well with morphologic measurements based on angiographic and histologic study. CONCLUSIONS MR implanted coil technology affords imaging of the arterial lumen and wall, allowing temporal assessment of the morphologic changes due to intimal hyperplasia after balloon dilation and may enable the evaluation of novel techniques to eliminate restenosis.
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Affiliation(s)
- J C Ford
- Department of Radiology, University of Pennsylvania Medical Center, Philadelphia 19104, USA
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